The periodic components of the precipitation and temperature data are analyzed in association with each other in this section. Table 6 shows the cross correlations between the D component of the precipitation data and the D component of the temperature data for the period 1951–2005. The larger correlation indicates the stronger relationship between the variables. The significance of a correlation was determined by the Student t-test at the significance level of p = 0.01. The correlations between the observed annual average temperature and the annual precipitation data do not generally have a significant value at the 1% significance level (for instance, its value is 0.27 for the Aydın data). On the other hand, the cross correlations of the long-term periodical components (such as D4, D5) show that 14 out of 16 data have a significance correlation (most of them are positive) at the 1% significance level. For example, the cross correlation between the D4 component of the precipitation data and the D4 component of the temperature data is 0.70 for İzmir data. The D4 component shows clearly stronger positive correlation than the correlations found in the observed data. On the other hand, it is worth noting that the D5 component shows very strong negative correlation at five out of eight stations. For instance, the correlation value of the D5 component at Muğla station is −0.82. Contrary to the D5 component, the correlation between the observed precipitation and air temperature data at Muğla station is positive (its value is 0.24). Similarly, the significance relationship between the approximate series is emphasized. These results show that there is a meaningful relationship between the long-term periodicity of the precipitation and temperature data.

Table 6

Cross correlations between precipitation and temperature data for the period 1951–2005

DataMuğlaİzmirAydınManisaEdirneBursaAfyonEskişehir
Observed 0.24 0.24 0.27 0.27 0.49* 0.07 0.12 0.17
D1 0.45* 0.20 0.48* 0.37* 0.34 0.11 0.29 0.29
D2 0.04 0.07 −0.20 0.08 −0.20 −0.32 −0.39* −0.43*
D3 −0.15 0.10 −0.27 0.32 −0.61* 0.08 0.33 0.44*
D4 0.77* 0.70* 0.45* 0.73* 0.41* 0.46* 0.66* −0.34
D5 −0.82* −0.59* −0.55* −0.67* 0.31 −0.65* 0.60* 0.55*
0.13 0.75* 0.48* −0.32 0.56* 0.38* 0.82* 0.82*
DataMuğlaİzmirAydınManisaEdirneBursaAfyonEskişehir
Observed 0.24 0.24 0.27 0.27 0.49* 0.07 0.12 0.17
D1 0.45* 0.20 0.48* 0.37* 0.34 0.11 0.29 0.29
D2 0.04 0.07 −0.20 0.08 −0.20 −0.32 −0.39* −0.43*
D3 −0.15 0.10 −0.27 0.32 −0.61* 0.08 0.33 0.44*
D4 0.77* 0.70* 0.45* 0.73* 0.41* 0.46* 0.66* −0.34
D5 −0.82* −0.59* −0.55* −0.67* 0.31 −0.65* 0.60* 0.55*
0.13 0.75* 0.48* −0.32 0.56* 0.38* 0.82* 0.82*

*Indicates significant correlation coefficients at p = 1%.

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